Rated 5 out of 5 stars

thanks for the answer.

I noticed that in the forwarding window, the mail account from which the email is being forwarded is shown. In my opinion, it would be better to display only the outgoing mail servers. Sometimes, the incoming and outgoing mail providers are not the same.

28.1.0esr (64-Bit)

Senden der Nachricht fehlgeschlagen.
Fehler beim Senden der Nachricht. Der Mail-Server antwortete: You are not allowed to use the domain icloud.com as DATA From domain.. Bitte überprüfen Sie die Nachricht und wiederholen Sie den Vorgang.

This review is for a previous version of the add-on (1.45). 

Some providers don't accept mails if the From: address is not from their own domain. You can try using another provider to redirect mails, e.g. google.